29 February 2016

MPLS-TE FRR Link Protection

These
weeks I have been working with Metro
Ethernet technologies like E-Line
VPWS and E-LAN VPLS to make Layer 2 VPN point to point or
multipoint to multipoint. A multipoint to multipoint service can be
made with VPLS tecnology that it
allows
us to simulate a big virtual private switch between our sites
which is useful if we want to have layer two connectivity between
datacenters. For instance, we could move virtual machines between
datacenters easily if we have an hypervisor in each data-center,
although they are in different cities.

However, I
want to talk about Traffic Engineering over MPLS this time. At
the beginning, MPLS was used by service providers because it
was too fast to switch labels instead of routing IPs but with the
last technological advances in hardware acceleration for routing in
the data plane like CEF (Cisco Express Forwarding)their
time or delays are the same. Nevertheless, MPLS can be an
interesting technology for Traffic Engineering if we combine it with
RSVP and a dynamic routing protocol with traffic engineering
extensions like OSPF and IS-IS.

What can
we do with traffic engineering? Mainly, we will be able to have more
resiliency and resource reservation. For instance, we could reserve
bandwidth in some links, force a specific path, avoid some routers
or hops, or choose a path with a specific delay and jitter to comply
with SLAs and QoS. In addition, we can configure MPLS-TE in our
network to use links more efficiently because it
allows
us to use several links at the same time.

Next, we
are going to see how we can configure the Fast ReRouting (FRR) Link
Protection which allows us to have alternative paths or backup paths
that it will be used in less than 50 ms if there is problems with the
main path. Note that this technique is faster than waiting the
convergence of a dynamic routing protocol. The topology of the lab is
the next:

Network Topology

While we can see the configuration in the next video:

With this
kind of technique we will have a more reliable network to meet with
the requirements and SLA of our customers.

Regards my
friend and remember, drop me a line with the first thing you are
thinking.